An urban rail communication-based train control (CBTC) system is responsible for the safe and efficient control of the trains. An advantage of a CBTC system is that increased reliability and closer spacing between trains is achievable during train operations. In a CBTC system, automatic train operation, protection, and supervision are often provided by central computers. These computers are responsible for the efficient routing of the trains and protection the trains from collision with other trains and derailing due to misaligned points (rail switches). The computer equipment on-board a train is directly responsible for adhering to the movement authority limits established by the control computers, reporting the position of the train, and for safely controlling the train propulsion system and the passenger doors. The components of the CBTC system are interconnected through a data communication system (DCS). The DCS must ensure that there is sufficient security in place to allow the safe, efficient operation of the CBTC system.